An electronic apparatus with an audio output, such as a computer, a walkman, a mobile phone, PDA (Personal Digital Assistant), an MP3 (Moving Picture Experts Group Audio Layer III) and an MP4 (Moving Picture Experts Group Audio Layer IV), etc., is usually provided with an audio jack available for connecting an earphone or an external speaker to facilitate a user to select use of an earphone for listening or use of a speaker to enlarge the audio range. A 3.5 mm earphone interface is widely used in the design of audio jacks of various electronic apparatuses. However, different industries have different definitions of the pins of the plugs of earphones. The audio jacks of electronic apparatuses should be designed differently to be adapted for the earphone plugs of the specifications of different industries and accordingly, the PCBs (Printed Circuit Boards) of these electronic apparatuses should be designed differently.
FIG. 1a is a schematic diagram of the pin definition of an earphone plug in conformity with CTIA (Cellular Telecommunications & Internet Association) specification. As shown in FIG. 1a, in accordance with the pin definition of the CTIA specification, the earphone plug 100 starts from an insertion end, and has an audio left pin 111, an audio right pin 112, a GND pin 113 and an MIC pin 114, respectively. It can be seen that the innermost pin of the earphone plug in conformity with the CTIA specification is the MIC pin. FIG. 1b is a schematic diagram of the pin definition of an earphone plug 119 in conformity with OMTP (Open Mobile Terminal Platform) specification. As shown in FIG. 1b, in accordance with the pin definition of the OMTP specification, the earphone plug 119 starts from an insertion end 120, and has an audio left pin 121, an audio right pin 122, an MIC pin 123 and a GND pin 124, respectively. It can be seen that the innermost pin of the earphone plug in conformity with the OMTP specification is the GND pin. It can be seen from FIGS. 1a and 1b, the MIC pin and the GND pin are interchanged for the earphone plugs of different specifications.
FIG. 2a is a schematic diagram showing a design of an audio jack 210 in conformity with the CTIA specification. As shown in FIG. 2a, the audio jack has seven conductive terminals 211-217; wherein the conductive terminal 211 is connected to the MIC pin of the earphone plug, the conductive terminal 212 is connected to the GND pin of the earphone plug, the conductive terminal 216 is connected to the audio right pin of the earphone plug, the conductive terminal 213 is connected to the audio left pin of the earphone plug, and the conductive terminals 214 and 215 are detection terminals. In addition, each of the conductive terminals is respectively connected to each of the pins of the PCB of the audio jack.
FIG. 2b is a schematic diagram showing a design of an audio jack 220 in conformity with the OMTP specification. As shown in FIG. 2b, the audio jack has seven conductive terminals 221-226; wherein the conductive terminal 221 is connected to the GND pin of the earphone plug, the conductive terminal 222 is connected to the MIC pin of the earphone plug, the conductive terminal 226 is connected to the audio right pin of the earphone plug, the conductive terminal 223 is connected to the audio left pin of the earphone plug, and the conductive terminals 224 and 225 are detection terminals. Likewise, each of the conductive terminals is furthermore connected to each of the pins of the PCB 227 of the audio jack, respectively.